Over the past decade a number of chemical companies have begun to develop infrastructures for the production of compounds using bio-based processes. Considerable progress has been reported toward new processes for producing commodity chemicals such as ethanol, lactic acid, 1,3-propanediol, and adipic acid. In addition, advances have been made in the genetic engineering of microbes for higher value specialty compounds such as acetate, polyketides, and carotenoids.
Pyruvate is a starting material for synthesizing a variety of biofuels and chemicals. Industrially, pyruvate is produced via dehydration and decarboxylation of calcium tartrate, a byproduct of the wine industry. This process involves toxic solvents and is energy intensive with an estimated production cost of $8,650 per ton of pyruvate. Microbial pyruvate production is based primarily upon two microorganisms, a multi-vitamin auxotroph of the yeast T. glabrata and a lipoic auxotroph of E. coli containing an F1ATPase mutation. The estimated cost of pyruvate production via microbial fermentation with such strains is estimated to be $1,255 per ton of pyruvate, an 85% savings. Increasing the yield of pyruvate would increase the savings even further.
Ethanol is mainly of interest as a petrol additive, or substitute, because ethanol-blended fuel produces a cleaner, more complete combustion that reduces greenhouse gas and toxic emissions. The production of ethanol in the US has increased tremendously in recent years, and demand is projected to increase even further. As a consequence of the surge in demand for biofuels, ethanol-producing microorganisms are of considerable interest due to their potential for the production of bioethanol. To keep in step with the growing demand for biofuels, the engineering of new strains of fermentative microorganisms that can efficiently produce ethanol will be required.
There is a need for microorganisms that efficiently produce pyruvate, ethanol, or other commodity chemicals.